Compared with the transverse isotropic(TI)medium,the orthorhombic anisotropic medium has both horizontal and vertical symmetry axes and it can be approximated as a set of vertical fissures developed in a group of hori...Compared with the transverse isotropic(TI)medium,the orthorhombic anisotropic medium has both horizontal and vertical symmetry axes and it can be approximated as a set of vertical fissures developed in a group of horizontal strata.Although the full-elastic orthorhombic anisotropic wave equation can accurately simulate seismic wave propagation in the underground media,a huge computational cost is required in seismic modeling,migration,and inversion.The conventional coupled pseudo-acoustic wave equations based on acoustic approximation can be used to significantly reduce the cost of calculation.However,these equations usually suffer from unwanted shear wave artifacts during wave propagation,and the presence of these artifacts can significantly degrade the imaging quality.To solve these problems,we derived a new pure P-wave equation for orthorhombic media that eliminates shear wave artifacts while compromising computational efficiency and accuracy.In addition,the derived equation involves pseudo-differential operators and it must be solved by 3D FFT algorithms.In order to reduce the number of 3D FFT,we utilized the finite difference and pseudo-spectral methods to conduct 3D forward modeling.Furthermore,we simplified the equation by using elliptic approximation and implemented 3D reverse-time migration(RTM).Forward modeling tests on several homogeneous and heterogeneous models confirm that the accuracy of the new equation is better than that of conventional methods.3D RTM imaging tests on three-layer and SEG/EAGE 3D salt models confirm that the ORT media have better imaging quality.展开更多
Conventional land vertical seismic profiling （VSP） exploration usually uses P-wave sources and three-component geophones for receivers, emphasizing P- and converted S-waves. Previous studies show that both dynamite ...Conventional land vertical seismic profiling （VSP） exploration usually uses P-wave sources and three-component geophones for receivers, emphasizing P- and converted S-waves. Previous studies show that both dynamite borehole shots and vertical vibrations from controllable seismic sources at the surface will produce relatively strong pure P-waves and weaker pure S-waves. Interfaces with a large Poisson＇s ratio difference have a positive influence on the formation of strong transmitted converted S-waves. By a comparative analysis of pure S-waves from sources and converted downgoing S-waves, we believe that the main frequency of pure S-waves is usually lower than pure P-waves while the main frequency of downgoing converted S-waves is close to that of P-waves. We have studied zero-offset and offset VSP data from land P-wave sources. Results show that pure S-waves commonly exist in these data with differences in wave intensity. S-wave velocity can be obtained from the P-wave source zero-offset VSP data. Finally, we discuss the bright future of joint application of VSP P-and S-waves and the full use of S-waves in P-wave source VSP data.展开更多
The anisotropic properties of subsurface media cause waveform distortions in seismic wave propagation,resulting in a negative infl uence on seismic imaging.In addition,wavefields simulated by the conventional coupled ...The anisotropic properties of subsurface media cause waveform distortions in seismic wave propagation,resulting in a negative infl uence on seismic imaging.In addition,wavefields simulated by the conventional coupled pseudo-acoustic equation are not only aff ected by SV-wave artifacts but are also limited by anisotropic parameters.We propose a least-squares reverse time migration(LSRTM)method based on the pure q P-wave equation in vertically transverse isotropic media.A fi nite diff erence and fast Fourier transform method,which can improve the effi ciency of the numerical simulation compared to a pseudo-spectral method,is used to solve the pure q P-wave equation.We derive the corresponding demigration operator,migration operator,and gradient updating formula to implement the LSRTM.Numerical tests on the Hess model and field data confirm that the proposed method has a good correction eff ect for the travel time deviation caused by underground anisotropic media.Further,it signifi cantly suppresses the migration noise,balances the imaging amplitude,and improves the imaging resolution.展开更多
目的:探索乳腺黏液癌(mucinous breast carcinoma,MBC)在多模态超声(multi-parametric ultrasonography,mpUS)即常规超声、剪切波弹性成像(shear wave elastography,SWE)及超声造影(contrast-enhanced ultrasound,CEUS)中的影像学特征,...目的:探索乳腺黏液癌(mucinous breast carcinoma,MBC)在多模态超声(multi-parametric ultrasonography,mpUS)即常规超声、剪切波弹性成像(shear wave elastography,SWE)及超声造影(contrast-enhanced ultrasound,CEUS)中的影像学特征,并评估其对MBC的诊断效能。方法:回顾并纳入2017年1月—2023年4月上海交通大学医学院附属第一人民医院因乳腺病变入院诊治的患者,以术后病理学检查为金标准。根据随机数字表法,按1∶1.5从同期患者中随机选取乳腺纤维腺瘤(fibroadenoma,FA)患者作为对照组。按照乳腺影像报告和数据系统(breast imaging reporting and data system,BI-RADS)分析影像学特征并进行分类。采用logistic回归筛选有效诊断指标,建立预测模型,绘制受试者工作特征曲线,以曲线下面积(area under curve,AUC)评估诊断效能。结果:最终纳入40例MBC患者共40个病灶,包括16例单纯型MBC(pure MBC,PMBC)、24例混合型MBC(mixed MBC,MMBC);60例FA患者,共60个病灶。在常规超声上,50.0%(8/16)的PMBC为BI-RADS 3及4A类,70.8%(17/24)的MMBC为BI-RADS≥4B类。SWE中PMBC和MMBC较FA更多呈不均质质硬表现(62.0%和83.3%vs 25.0%),3~4分是两者与FA鉴别的独立预测因素。CEUS中病变内存在囊性无增强区、边缘增多滋养血管是PMBC与FA鉴别的独立风险因素。相较于MMPC,mpUS较单独常规超声能更显著地提升PMBC与FA的鉴别诊断效能(AUC:0.949 vs 0.858,P<0.05)。结论:MBC,尤其是PMBC,因其与FA在常规超声声像图上存在重叠征象而常被低估,采用mpUS较单独使用常规超声可显著提高其与FA的鉴别诊断效能。展开更多
目的探讨基于DEA-RSR模型对超声设备运行效率的管理,评估2021—2023年湖州市妇幼保健院超声设备运行效率,为设备管理与资源配置提供科学依据。方法以12个季度超声设备数据为样本,筛选“医技人员数量、维修费、设备数量”为投入指标,“...目的探讨基于DEA-RSR模型对超声设备运行效率的管理,评估2021—2023年湖州市妇幼保健院超声设备运行效率,为设备管理与资源配置提供科学依据。方法以12个季度超声设备数据为样本,筛选“医技人员数量、维修费、设备数量”为投入指标,“诊断人次、总收入”为产出指标;采用数据包络分析(Data Envelopment Analysis,DEA)模型测算效率并识别投入冗余与产出不足问题;结合秩和比综合评价法(Rank Sum Ratio,RSR)对各季度效率进行综合排序与分档。结果DEA分析显示,12个季度超声设备综合效率的平均值为0.944。其中,有6个季度资源配置达到DEA强有效水平,另6个季度则表现为非DEA有效,表明存在投入冗余和产出不足问题;RSR将超声设备运行效率划分为“差”“中”“好”三档,其中差级有1个季度,中级有9个季度,好级有2个季度,且RSR与概率单位呈高度正相关。结论DEA-RSR模型在优化设备运行效率方面具有一定可行性,可通过对设备运行效率的准确评估,为医院管理者提供针对性的资源调配建议,从而提升设备利用率及服务质量。展开更多
For a typical marine shale reservoir in the Jiaoshiba area, Sichuan Basin of China, P-impedance is sensitive for identifying lithology but not suitable for indicating good shale reservoirs. In comparison, density is a...For a typical marine shale reservoir in the Jiaoshiba area, Sichuan Basin of China, P-impedance is sensitive for identifying lithology but not suitable for indicating good shale reservoirs. In comparison, density is an important quantity, which is sensitive for identifying the organic-rich mud shale from non-organic-rich mud shale. Due to the poor data quality and incidence angle range, density cannot be easily inverted by directly solving the ill-posed pre-stack seismic inversion in this area. Meanwhile, the traditional density regularizations implemented by directly using the more robust P-impedance inversion tend to be inaccurate for recovering density for this shale reservoir. In this paper, we combine the P-impedance and the minus uranium to construct the pseudo-P-impedance（PIp） at well locations. The PIp is observed to be sensitive for identifying organic-rich mud shale and has a good correlation with density in this area. We employ the PIp–density relation into the pre-stack inversion framework to estimate density. Three types of regularization are tested on both numerical and field data： These are no regularization, traditional regularization and the proposed approach. It is observed that the proposed method is better for recovering the density of organic-rich mud shale in the Jiaoshiba area.展开更多
基金supported by the Marine S&T Fund of Shandong Province for Pilot National Laboratory for Marine Science and Technology(No.2021QNLM020001)the Major Scientific and Technological Projects of Shandong Energy Group(No.SNKJ2022A06-R23)+2 种基金the Funds of Creative Research Groups of China(No.41821002)National Natural Science Foundation of China Outstanding Youth Science Fund Project(Overseas)(No.ZX20230152)the Major Scientific and Technological Projects of CNPC(No.ZD2019-183-003)。
文摘Compared with the transverse isotropic(TI)medium,the orthorhombic anisotropic medium has both horizontal and vertical symmetry axes and it can be approximated as a set of vertical fissures developed in a group of horizontal strata.Although the full-elastic orthorhombic anisotropic wave equation can accurately simulate seismic wave propagation in the underground media,a huge computational cost is required in seismic modeling,migration,and inversion.The conventional coupled pseudo-acoustic wave equations based on acoustic approximation can be used to significantly reduce the cost of calculation.However,these equations usually suffer from unwanted shear wave artifacts during wave propagation,and the presence of these artifacts can significantly degrade the imaging quality.To solve these problems,we derived a new pure P-wave equation for orthorhombic media that eliminates shear wave artifacts while compromising computational efficiency and accuracy.In addition,the derived equation involves pseudo-differential operators and it must be solved by 3D FFT algorithms.In order to reduce the number of 3D FFT,we utilized the finite difference and pseudo-spectral methods to conduct 3D forward modeling.Furthermore,we simplified the equation by using elliptic approximation and implemented 3D reverse-time migration(RTM).Forward modeling tests on several homogeneous and heterogeneous models confirm that the accuracy of the new equation is better than that of conventional methods.3D RTM imaging tests on three-layer and SEG/EAGE 3D salt models confirm that the ORT media have better imaging quality.
文摘Conventional land vertical seismic profiling （VSP） exploration usually uses P-wave sources and three-component geophones for receivers, emphasizing P- and converted S-waves. Previous studies show that both dynamite borehole shots and vertical vibrations from controllable seismic sources at the surface will produce relatively strong pure P-waves and weaker pure S-waves. Interfaces with a large Poisson＇s ratio difference have a positive influence on the formation of strong transmitted converted S-waves. By a comparative analysis of pure S-waves from sources and converted downgoing S-waves, we believe that the main frequency of pure S-waves is usually lower than pure P-waves while the main frequency of downgoing converted S-waves is close to that of P-waves. We have studied zero-offset and offset VSP data from land P-wave sources. Results show that pure S-waves commonly exist in these data with differences in wave intensity. S-wave velocity can be obtained from the P-wave source zero-offset VSP data. Finally, we discuss the bright future of joint application of VSP P-and S-waves and the full use of S-waves in P-wave source VSP data.
基金financially supported by the National Key R&D Program of China (No. 2019YFC0605503)the Major Scientific and Technological Projects of CNPC (No. ZD2019-183-003)the National Natural Science Foundation of China (No. 41922028,41874149)。
文摘The anisotropic properties of subsurface media cause waveform distortions in seismic wave propagation,resulting in a negative infl uence on seismic imaging.In addition,wavefields simulated by the conventional coupled pseudo-acoustic equation are not only aff ected by SV-wave artifacts but are also limited by anisotropic parameters.We propose a least-squares reverse time migration(LSRTM)method based on the pure q P-wave equation in vertically transverse isotropic media.A fi nite diff erence and fast Fourier transform method,which can improve the effi ciency of the numerical simulation compared to a pseudo-spectral method,is used to solve the pure q P-wave equation.We derive the corresponding demigration operator,migration operator,and gradient updating formula to implement the LSRTM.Numerical tests on the Hess model and field data confirm that the proposed method has a good correction eff ect for the travel time deviation caused by underground anisotropic media.Further,it signifi cantly suppresses the migration noise,balances the imaging amplitude,and improves the imaging resolution.
文摘目的:探索乳腺黏液癌(mucinous breast carcinoma,MBC)在多模态超声(multi-parametric ultrasonography,mpUS)即常规超声、剪切波弹性成像(shear wave elastography,SWE)及超声造影(contrast-enhanced ultrasound,CEUS)中的影像学特征,并评估其对MBC的诊断效能。方法:回顾并纳入2017年1月—2023年4月上海交通大学医学院附属第一人民医院因乳腺病变入院诊治的患者,以术后病理学检查为金标准。根据随机数字表法,按1∶1.5从同期患者中随机选取乳腺纤维腺瘤(fibroadenoma,FA)患者作为对照组。按照乳腺影像报告和数据系统(breast imaging reporting and data system,BI-RADS)分析影像学特征并进行分类。采用logistic回归筛选有效诊断指标,建立预测模型,绘制受试者工作特征曲线,以曲线下面积(area under curve,AUC)评估诊断效能。结果:最终纳入40例MBC患者共40个病灶,包括16例单纯型MBC(pure MBC,PMBC)、24例混合型MBC(mixed MBC,MMBC);60例FA患者,共60个病灶。在常规超声上,50.0%(8/16)的PMBC为BI-RADS 3及4A类,70.8%(17/24)的MMBC为BI-RADS≥4B类。SWE中PMBC和MMBC较FA更多呈不均质质硬表现(62.0%和83.3%vs 25.0%),3~4分是两者与FA鉴别的独立预测因素。CEUS中病变内存在囊性无增强区、边缘增多滋养血管是PMBC与FA鉴别的独立风险因素。相较于MMPC,mpUS较单独常规超声能更显著地提升PMBC与FA的鉴别诊断效能(AUC:0.949 vs 0.858,P<0.05)。结论:MBC,尤其是PMBC,因其与FA在常规超声声像图上存在重叠征象而常被低估,采用mpUS较单独使用常规超声可显著提高其与FA的鉴别诊断效能。
文摘目的探讨基于DEA-RSR模型对超声设备运行效率的管理,评估2021—2023年湖州市妇幼保健院超声设备运行效率,为设备管理与资源配置提供科学依据。方法以12个季度超声设备数据为样本,筛选“医技人员数量、维修费、设备数量”为投入指标,“诊断人次、总收入”为产出指标;采用数据包络分析(Data Envelopment Analysis,DEA)模型测算效率并识别投入冗余与产出不足问题;结合秩和比综合评价法(Rank Sum Ratio,RSR)对各季度效率进行综合排序与分档。结果DEA分析显示,12个季度超声设备综合效率的平均值为0.944。其中,有6个季度资源配置达到DEA强有效水平,另6个季度则表现为非DEA有效,表明存在投入冗余和产出不足问题;RSR将超声设备运行效率划分为“差”“中”“好”三档,其中差级有1个季度,中级有9个季度,好级有2个季度,且RSR与概率单位呈高度正相关。结论DEA-RSR模型在优化设备运行效率方面具有一定可行性,可通过对设备运行效率的准确评估,为医院管理者提供针对性的资源调配建议,从而提升设备利用率及服务质量。
基金NSFC and Sinopec Joint Key Project (U1663207)the China Geology Survey Project (DD20160195)+2 种基金973 Program (2014CB239104)National Key S&T Projects (2017ZX05049002)China Postdoctoral Science Foundation for the financial support
文摘For a typical marine shale reservoir in the Jiaoshiba area, Sichuan Basin of China, P-impedance is sensitive for identifying lithology but not suitable for indicating good shale reservoirs. In comparison, density is an important quantity, which is sensitive for identifying the organic-rich mud shale from non-organic-rich mud shale. Due to the poor data quality and incidence angle range, density cannot be easily inverted by directly solving the ill-posed pre-stack seismic inversion in this area. Meanwhile, the traditional density regularizations implemented by directly using the more robust P-impedance inversion tend to be inaccurate for recovering density for this shale reservoir. In this paper, we combine the P-impedance and the minus uranium to construct the pseudo-P-impedance（PIp） at well locations. The PIp is observed to be sensitive for identifying organic-rich mud shale and has a good correlation with density in this area. We employ the PIp–density relation into the pre-stack inversion framework to estimate density. Three types of regularization are tested on both numerical and field data： These are no regularization, traditional regularization and the proposed approach. It is observed that the proposed method is better for recovering the density of organic-rich mud shale in the Jiaoshiba area.
